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Structure and Bonding: Step-by-Step Chemistry Series

May 8, 2020 — The WolframAlpha Chemistry Team

Structure and Bonding: Step-by-Step Chemistry Series

We’re back this week with more chemistry, to explore molecular structure and bonding with Wolfram|Alpha and its step-by-step chemistry offerings. Read more on chemical reactions and solutions from previous weeks, and join us next week for our final installment on quantum chemistry!

Structure and bonding in chemistry refer to where the atoms in a molecule are and what holds those atoms together. Molecules are held together by chemical bonds between the atoms comprising the molecule. Understanding the interplay between molecular structure and the electrons involved in bonding is what facilitates the design of new molecules, the control of chemical reactions and a better understanding of the molecules around us.

To master structure- and bonding-related calculations, the step-by-step solutions provide stepwise guides that can be viewed one step at a time or all at once. Read on for example problems covering Lewis structures, oxidation numbers and orbital hybridization.

Chemical Structure

Molecular species are not visible to the naked eye, so being able to represent them in a pictoral form is fundamental to communicating chemical information. One of the most common depictions is the Lewis structure. The step-by-step solution (introduced in 2013) walks you through counting the valence electrons, assigning them to each atom and determining the required number of bonds.

Example Problem

What is the Lewis structure of nitrogen dioxide, NO2?

Step-by-Step Solution

In this case, you can simply enter your query, “What is the Lewis structure of NO2”.

&ldqup;What is the Lewis structure of NO2”

Oxidation Numbers

Redox reactions are a huge class of chemical reactions involving the reduction of one reactant and the oxidation of another. In order to identify the reducing and oxidizing agents, the oxidation numbers for each element in a compound must be computed. The step-by-step solution walks you through partitioning bonding electrons and accounting for the electronegativity of each element.

Example Problem

Assign oxidation numbers to all of the elements in Na2SO4.

Step-by-Step Solution

For this type of problem, you can ask for “Na2SO4 oxidation numbers”.

“Na2SO4 oxidation numbers”

Orbital Hybridization

Atomic orbitals of similar energy and the same symmetry can mix to form hybrid orbitals. These hybrid orbitals directly affect the three-dimensional arrangement of atoms in a molecule. The step-by-step solution explains how to determine orbital hybridization from the structure diagram and steric numbers.

Example Problem

What is the hybridization on each atom in succinylacetone?

Step-by-Step Solution

Finding the hybridization is easy when you enter “succinylacetone hybridization”.

“succinylacetone hybridization”

Challenge Problems

Test your problem-solving skills by using the Wolfram|Alpha tools described to solve these word problems on structure and bonding. Answers will be provided in the next blog post in this series.

  1. What is the oxidation state of hydrogen in lithium aluminum hydride?
  2. What is the orbital hybridization of the central atom in SF6?


Answers to Last Week’s Challenge Problems

Here are the answers to last week’s challenge problems on chemical solutions.

1. A good ratio for the salt bath used in old-fashioned ice-cream makers is five cups ice to one cup salt. What is the mass fraction of the resulting mixture?

The volume-to-mass conversions need to be done in two separate Wolfram|Alpha queries.

“mass of five cups ice”

“convert one cup salt to mass”

Then pass the results into a mass fraction query.

“mass fraction 511 g salt in 1.084 kg ice”

2. What is the molality of ethylene glycol for a solution that freezes at –5.00 °C?

First, look up the cryoscopic constant for ethylene glycol.

“cryoscopic constant ethylene glycol”

Next, plug the retrieved information into the freezing-point depression calculator.

“freezing point depression Kf=3.11 K kg/mol, i=1, Tf=-5C”

Join us next week for our final installment on quantum chemistry. And as always, if you have suggestions for other step-by-step content (in chemistry or other subjects), please let us know! You can reach us by leaving a comment below or sending in feedback at the bottom of any Wolfram|Alpha query page.

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